1. Field of the Invention
The present invention relates to a display device for displaying operating status of an industry machine used as production equipment, preferably, a machine tool.
2. Description of the Related Art
In a machine tool, a display control panel is used therein to display an operator operating status data representing operating status of the machine tool by reading out from a PLC for controlling the machine tool. The display control panel is provided with a display device.
In the display device of the above-mentioned control panel, there is used a CRT display or a LCD panel generally on which clear touch panel is superimposingly therewith arranged so as to be operable of touch input from an operator. A displayed screen is changed by this touch operation of the operator, and operating command to a control device can be performed. Contents of the operating status data are represented by displayed status of plural touch switches displayed on a predetermined section of the display device. Generally, contents of the operating status data representing execution status of operating process and operating status of the machine are displayed as touch switched. An example of thus control panel is described in Japanese Patent Application No. H8(1996)-107631.
Besides, the operating status data in this specification represents input data from various sensors installed in the production equipment, output data to actuators for operating the production equipment, input/output data with other control device controlling the machine tool, or data that is memorized into an internal memory of the PLC and is executed by sequence program based upon the aforementioned data.
Thus control panel is used as a operating monitor of the machine tool and is also used for searching causation of abnormal data when generated. In the causation that the machine tool does not operate normally, one is a device error that the device does not work with a breakdown. The other is a silent abnormal stop that the operating process is stopped when the condition for advancing the operating processes is not satisfied. In the silent abnormal stop, the causation is of that it is not recognized by an operating error of a limit switch whether a workpiece is transferred in from the production equipment in former process, and is of that a clamping operation is not completed formally at a clamping position of a workpiece by positioning error of the workpiece.
In a case of the device error, generated portion and causation of the operating error can be directly judged by such an error code, an LED representing an error status, and an error message displayed on the displayed screen of the control panel, etc. On the other hand, the operating error in the silent abnormal stop is noticed to the operator when a monitoring device of the production line detects a long-time stop of the machine. However, it is difficult to directly obtain error information for specifying causation of the operating error differently from the device error. In this situation, the operator presumes the causation of the operating error from the displayed status of the touch switch on the control panel. Further, the causation of the operating error is surveyed by an auxiliary device having compiling and monitoring function of the sequence program, if necessary.
However, problems described hereinbelow occurs when a surveillance of the causation in the silent abnormal stop is carried out by the method described above. Namely, it can be facilitated to judge which operating process in the production equipment is stopped due to the displayed status of the touch switch. Reversely, it cannot be judge how that operating process with the silent abnormal stop stops from the displayed status of the touch switch. If the operating process of the machine tool stops in a case that the displayed status of the touch switch represents “FIXTURE CLAMP” of the present operating process, it can be understood that the operating error occurs in “FIXTURE CLAMP” of the operating process, for example. There are however plural conditions for occurring the operating stop in “FIXTURE CLAMP” of the operating process, so that it cannot recognized which condition causes the operating error.
In this situation, it may be required to use the auxiliary device having the compiling and monitoring function of the sequence program. But, it is requested to bring the auxiliary device to the side of the production equipment (i.e., the control panel) for connecting the same therewith, and to supply the electric power thereto by wiring. It is further requested to wire the auxiliary device with the PLC for communication in order to transfer the sequence program stored therein to the auxiliary device. In such a situation, a sequence circuit block is searched to analyze the problematic operating process, and the present value of the related input/output signal is monitored by using the online monitoring function. As a result, the causation of the operating error can be specified. Thus, such a problem occurs that it is excessively time-spent to specify the operating error.